High-speed printers are often used to print large numbers of labels from rolls of blank labels. High-speed printers may be printers with banks of ink-jet printer heads, of thermal printheads, a laser printer or other type of printer. The printer is adapted to receive a continuous web of labels from a roll of labels. The printer may be computer controlled to print different text, graphics or other indicia on each label. For example, the printer may print a different addressee and address on thousands of mailing labels to be applied to a subscription magazine.
These high-speed printers are often in great demand and required to operate continuously for large periods of time. For example, a magazine publisher ready to publish a weekly magazine must rapidly produce hundreds of thousands of labels in order to mail the magazine in a timely manner. The printer of such large numbers of labels for a magazine subscription requires nearly continuous operations of a large number of high speed label printers. Even a relatively small business office may have one or more label printers that are nearly continuously operated to print labels for mailing correspondence, packages and other materials to customers. Accordingly, there is a strong need for label printers that can continuously print labels without undue or frequent interruptions.
Printing labels is particularly difficult due to the excess toner, printing ink, paper dust, adhesive residue, and other debris that tends to clog the printers, especially printer nozzles. Labels present unusual difficulties to a printer because labels are often multi-ply forms, e.g., a liner and removable label, and because labels usually have adhesive coatings that clog printers and attract paper dust and other debris. Some of the adhesive from the adhesive coatings of labels may be left as a residue on the printer as each label passes through the printer. The tendency for some adhesive to stick to the printer is disadvantageously increased because multi-ply labels have additional web edges that may carry adhesive residue that attaches to the printer.
The adhesive residue left on printers, and especially printheads, by labels disrupts printing. The adhesive itself can clog printheads and disrupt the printing of clear, readable text on labels. In addition, when adhesive residue coats a printhead, the adhesive tends to be tacky or sticky. The stickiness of the adhesive attracts paper dust, extraneous ink and other debris which can also clog printheads.
The printers require regular cleaning to unclog printheads, and to remove adhesive and other debris material from the printheads. In the past, cleaning cards have been used to manually clean printers. The cleaning cards were soaked in a cleaning solvent and stored in sealed bags to prevent evaporation of the solvent. When a printer was to be cleaned, the printer was stopped, the label web may or may not have been removed from the printer and a cleaning card manually inserted into the printer between the printhead and platen. This use of cleaning cards disrupted normal printing operations and the feeding of label stock through the printers. In addition, the prior art printer cards, e.g., a 3 inch by 5 inch, or 4 inch by 6 inch card, required printer operators to schedule frequent cleaning operations and to adhere to that cleaning schedule. Failure to follow the prescribed cleaning schedule would lead to clogged printers, which resulted in poor print quality and having to shut down the printer at unscheduled times. Accordingly, prior art cleaning techniques using cleaning cards were necessary to maintain the printers, but caused disruptions to printing and imposed additional duties on print operators. There was a long felt need for a device and a method for cleaning printers that did not unnecessarily disrupt print operations, provided regular cleaning of the printer, and did not require printer operators to manually clean the printer or to follow a cleaning schedule (in addition to their other duties).
In addition, conventional printer cleaning cards were not satisfactory. For example, the conventional wisdom is that the solvent in the cleaning cards was isopropyl alcohol. Isopropyl alcohol is not particularly effective in cleaning adhesives and the other debris associated with printing labels. Recently, a terpene-based solvent has been used to soak thermal printer cleaning cards. Terpene solvents are effective at softening adhesives and for cleaning printers having adhesive residue. Terpene cleaning cards and/or terpene solvents are available from the Texwipe Company of Upper Saddle River, N.J. (U.S.A.); Planna Technology Inc. of Minneapolis, Minn. (U.S.A.) and Moore U.S.A. of Grand Island, N.Y. (U.S.A.). Terpene based solvents may include vegetable seed oil (esters), nonionic surfactants, inorganic water conditioner in suspension, anti-foaming agents and de-ionized water, or (alternatively) d-limonene, myrcene, alpha-pinene, linalool, octanal, and glycol ether DPM.
However, conventional printer cleaning cards have tended to be problematic. Such cleaning cards have been formed of paper card substrates or other non-woven materials such as polyester. The advantage of paper cards and non-woven fibers is that they are relatively rigid and stiff, which assists in inserting the card into the printer and in scraping off contaminants from the printer. In addition, paper and other non-woven substrates have a fiber length that is relatively short. When these short fibers from the cards are left in the printer they are less likely to clog the printer or interfere with printer operation than would the long fibers of a woven card or cloth. It is conventional wisdom that the long fibers of woven substrates are more likely than are short fibers to attach to the printhead when those long fibers separate from the print card and are left in the printer. However, paper substrates and other short fiber substrates do not retain solvents well and tend to leave too much solvent on the printer and platen roller. An attempt to overcome the shortcomings of paper card substrates has been made in which a ribbed cloth is apply to a polycard, but this attempt (which did used an abrasive rather than a terpene solvent) is not effective in cleaning label printers.
Despite the conventional wisdom not to use long-fiber, woven substrates for cleaning cards, woven substrates do generally have a larger capacity to retain cleaning solvents than do paper substrates and other short fiber substrates. Woven, long fiber cards soak up solvents, in a similar manner to a towel (which is a woven, long fiber material) soaking up water. Some prior printer cleaning cloths have been marketed that are made of cloth toweletts, such as by Planna Technology Inc. While these cloth toweletts are effective (especially when soaked with a terpene solvent), they do not clean all contaminants off a printer. For example, removal of printing ink (similar to the ink in a ballpoint pen) is particularly difficult and was not removed by the Planna cloth towelett.
Applicant believes that a problem with prior cloth toweletts has been that the toweletts lack sufficient stiffness and thickness to be easily inserted into the printer or to adequately scrape off difficult contaminants from the printer. In particular, the toweletts are a single-ply cloth that quickly fold over when held upright on an edge. The toweletts have little stiffness, especially when compared to the paper card substrates that are as stiff as paper index cards. Accordingly, cloth toweletts have advantages over stiff paper cleaning cards, but the toweletts also suffer from disadvantages over paper cards. There has been a long-felt need for a printer cleaning card that combines the advantages of several different conventional cleaning cards and toweletts, is easy to use and does not interrupt the printing process solely for cleaning purposes.
The present invention solves many of the problems associated with prior printer cleaning cards and cleaning cloths. The present invention is a woven cleaning cloth formed from multiple layers of polypropylene, soaked in a terpene solvent. The layers of the polypropylene are bonded together by a sonic or thermal bonding process. The bonded, multi-layer cleaning cloth has sufficient rigidity and stiffness so as to stand-on end to be easily inserted into the nip of a printer, and to scrap off contaminants from the printheads.
In addition, the bonding of the multiplies of the cleaning cloth is accomplished to impress a pattern, e.g., cross-hatching, zig-zag, tire-tread, or company logo, into the cloth. The pattern assists in providing stiffness to the cleaning cloth and in scraping contaminants from the printer. In addition, the pattern is helpful in bonding the layers of the cloth together, and in holding long fibers in the cloth. Moreover, the pattern may be eye-pleasing or provide promotional information, such as a patter in a company logo.
In addition, the cleaning cloth of the present invention is attached as a leader (or ender) to a roll of labels. As the roll of labels is inserted into the printer the cleaning cloth is pushed or pulled through the printer and across the printhead. Because the cleaning cloth is relatively stiff, the cloth can be used as a leader for a roll of labels being inserted into a printer. Because the cleaning card is attached to a roll of labels, the printer is cleaned when the a new printer roll is added to the printer (or when an old roll of label has completely passed through the printer if the cleaning cloth is at the end of the roll). The end or beginning of a roll of labels pass through a printer during the label roll changeover, which is a normal time during which the printer is offline. Having the cleaning cloth wipe over the printer at the roll changeover does not disrupt the printing operation, any more than that which inherently occurs by the roll changeover.
Moreover, the cleaning duties of the printer operator have been substantially reduced by the present invention. The operator need only remove the cleaning cloth from its sealed pouch and attach it to a roll, just before the roll is inserted in the printer. In addition, the end of a roll of labels is usually much easier to access to attach a cleaning cloth, than it is to access the internal components, i.e., printhead, of a printer to manually wipe with a cleaning cloth or card. The operator also need not separately schedule cleaning of the printer with cleaning card, as was done previously. The cleaning with the inventive cleaning cloth occurs when the label roll is changed. All the operator has to remember to do is attach the cleaning cloth to the label roll. Accordingly, the invention has fulfilled several of the long-felt needs for a printer cleaning card.